Severe Chaffing Between Legs And Under Buttock Area. Desintin Helped. Permanent Relief ?

I have severe chaffing between my legs and under my buttock area. I am a diabetic and have had a UTI as well as a bacteria infection. Over the course of three months I have taken shots of cortisone for a menicus tear in my knee, predisone for 6 days, plus a shot for a rash developed by a food allergy , 3 rounds of antibiotics for bronchitis , sinusitis , earinfections, etc. antibiotics for the UTI and bacterial infection . My diabetes doctor put me on time released 500mg. of metformin for 2 wks. 1000 for 2 wks. 1500 for 2 wks and 2000 for 2wks to get my body acclaimated to the increase dosage because I had constant loose stools/upset stomach for 3 months with the 2000 mg of metformin twice a day. Question, currently nothing seems to help the burning sensation under my buttocks and between my legs. I have noticed some improvement between my legs and vaginal area since using desintin; however, no relief under my buttocks. Do you have any suggestions on what can be applied to the area to have some relief? Also, would sitting in a tub of cool or warm water help and if so which cool or warm? Thank you for your prompt response.